Protein is a nutrient needed by the human body for growth and maintenance. Aside from water, protein is the most abundant molecule in the body. According to U.S. and Canadian Dietary Reference Intake guidelines, women aged 19-70 need to consume 46 grams of protein per day, while men aged 19-70 need to consume 56 grams of protein per day to avoid deficiency. This recommendation, however, is for a sedentary person free of disease. Protein deficiency can lead to reduced intelligence or mental retardation as well as contribute to the prevalence of diseases such as kwashiorkor. Protein deficiency is a serious problem in developing countries, particularly, in countries affected by war, famine, and overpopulation. Animal sources of protein, such as meat, are often a source of the complete complement of all the essential amino acids in adequate proportions.
The nutritional benefits of meat are tempered by potential associated environmental degradation. According to a 2006 report by the Livestock, Environment And Development Initiative, entitled Livestock's Long Shadow—Environmental Issues and Options, the livestock industry is one of the largest contributors to environmental degradation worldwide, and modern practices of raising animals for food contributes widely to air and water pollution, land degradation, climate change, and loss of biodiversity. The production and consumption of meat and other animal sources of protein is also associated with the clearing of rainforests and species extinction. Accordingly, there is a need for a solution to demands for alternative to meat produced from live animals.